The present invention relates to a compressor for use, mainly, in a cooling, refrigeration and/or air-conditioning apparatuses.
Conventionally, as a valve for opening and/or closing a passage, through which coolant or refrigerant flows into and/or out in a reciprocating compressor and/or a rotary compressor for use in cooling, refrigeration and/or air-condition, in particular, the valve which is applied into a discharge port for discharging the refrigerant therefrom, it is common to use a valve of so-called a reed-type, in which a thin plate-like valve opens and/or close the port therewith.
With such the valve mentioned above, an end of the plate-like valve is disposed so that it closes an outlet portion of the discharge valve, through which the refrigerant flows out, while the other end thereof is fixed on a side of compressing element of the compressor (i.e., on the port side thereof), wherein the opening/closing of the valve is conducted automatically through pressure difference between an inside and an outside of the discharge port. Also, there is one, in which the valve is fixed onto the compressing element through a stopper.
Considering an improvement on performances of the compressor, working fluid (i.e., the refrigerant) lying within the volume of a part of the discharge port, i.e., a gap or clearance volume, will not be discharged when the compressor completes the discharge cycle or stroke thereof, therefore it remains therein. Namely, the refrigerant remaining in this part comes to be discharged by the compressor operation but does not effect the heat exchange, therefore an efficiency in the compressor operation is lowered down if such the refrigerant increases in the volume thereof.
The working fluid of high temperature and high pressure remaining in this clearance volume, after all, expands within a suction chamber of low pressure, and in particular, in a case of the reciprocating compressor, this expansion reduces the suction volume thereof, thereby bringing about the decreasing of volume efficiency. Also, since energy of this expansion cannot be recovered or collected in the case of the rotary compressor, it comes to be power loss (hereinafter, being called by “re-expansion loss”), therefore it brings about lowering of the performances in the compressor. The greater the loss due to this re-expansion loss, the larger the ratio of the clearance volume occupying within the stroke volume of the compressor. For example, according to studies made by the inventors of the present invention, it is found that adiabatic efficiency is reduced down by about 5% due to this re-expansion, in particular in the case of the rotary compressor that is used in a home-use refrigerator.
For dissolving such the problem of the reed valve, for example, U.S. Pat. Nos. 4,543,989 and 5,346,373 disclose discharge valve apparatuses, in which a discharge valve of a poppet-type is applied so as to bring the clearance volume to be almost zero (0).
In the above-mentioned U.S. Pat. No. 4,543,989 (prior art 1) is disclosed a compressor of the reciprocating-type, which comprises a discharge port having a valve of a conical-shape and a spherical shape, and a valve seat recessed in a conical-shape, wherein the valve bodies are engaged within the recess of the valve seat, so as to remove that clearance volume therein. With the structure according to this prior art, the valve and the valve seat, both in the conical shape, are in contact with each other upon contacting surfaces thereof, thereby enclosing the spaces in front and rear of the port. Further, the valve is restricted on displacement in the vertical direction and decentering in the horizontal direction, within a cylindrical vacant cavity of a retainer engaged with or fitted to a bridge member, being provided over an opening of the port, so that it cover the discharge port on a down-stream side thereof, and the valve is biased toward the valve seat by means of a wound leaf spring which is inserted into this cavity.
Further in the above-mentioned Pat. No. 5,346,373 (prior art 2), a discharge valve apparatus is disclosed, in which both the valve and the valve seat are formed in the spherical shapes, so that they enable to close up even if the valve are inclined to the valve seat, and further the valve is biased toward the valve seat by means of the thin plate-like spring.
In the above-mentioned prior art 1, the retainer is fixed onto the compressing element (a cylinder side) by screwing the bridge member, on which is engaged or fitted the retainer, however when the retainer is attached onto the valve seat in eccentric or decentering therefrom, i.e., in a case where the valve is assembled into the valve seat in decentering therefrom, the valve declines when seating, so that it is unable to fully contact with upon the surface thereof, thereby disabling the enclosure, and therefore the working liquid of high temperature and high pressure flows back into the suction chamber, thereby decreasing volume efficiency. For this reason, the retainer and the valve seat must be fixed in concentric with each other, at high accuracy, therefore it causes a problem that the number of processes in assembling increases up, as well as the cost thereof. Further, the discharge valve apparatus is large in the number of constituent parts and complex in the structure thereof, therefore the productivity thereof is decreased down.
Also, though it is easy for a large compressor, it is more difficult to make an adjustment on the compressor, if it comes to be smaller in the sizes thereof, and also the higher accuracy is needed for it, therefore it causes a problem of bringing about the cost-up, however this prior art never pay considerations onto such the problems.
Also, in this prior art, since the valve is pushed or projected into the operation chamber of the compressor, so that it collides on a piston, if a bottom surface of the valve lies on the same plane to that of a valve plate and if the valve declines, during the closure of the valve, there occurs a problem that both collide with each other, in particular in the case of the rotary compressor, in which the moving direction of the valve for opening/closing, as well as that of a roller thereof, lie in the vertical direction. No consideration was paid, however, on those problems in this prior art.
In the prior art 2 mentioned above, since no bias is applied onto the valve due to the spring force under the condition when the valve is closed, and further no means is provided for restricting the movement of the valve in the horizontal direction, a delay is caused in the closing operation thereof due to rebounding when the valve is seated on the valve seat and/or the inclination of the valve when it is seated in greatly eccentric or decentering to the valve seat, therefore it causes a problem that the working fluid of high temperature and high pressure flows back into the suction chamber, thereby decreasing the volume efficiency down.
Also, with the retainer, the spring and the valve, etc., the constituent parts of the discharge valve apparatus, since they must be treated separately when they are assembled, it is difficult to handle or deal with them if they become small in sizes thereof, for example, in case of being applied into the compressor of small capacity, such as the compressor of a refrigerator or an air-conditioner for home-use, thereby bringing about a problem of decreasing down workability in assembling, as well as the productivity thereof.
Also, since the valve projects into the operation chamber of the compressor while providing a gap or clearance for escaping at the top portion of the piston, the clearance volume comes to be large, and this cannot be applied to such the rotary compressor, in which the moving direction of the valve for opening/closing, as well as that of the roller thereof, lie in the vertical direction. No consideration was paid, however, on such the problem in this prior art 2.